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PCV breather debate

DiabloStang

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Could someone smart explain to me why routing a hose to the floor or using filter caps / breathers on the PCV valves is bad or good when applying it to a gen 2 coyote motor? I have a procharged s550 and would like to put a cone filter directly on the head unit (it just looks and sounds way cooler) Doing this would require me to modify the PCV setup ( its currently routed to the intake tube just upstream of the compress suction ).

I’ve seen post arguing that breather caps cause condensation to buildup in the engine, noticing a milk substance when taking the breather caps off. However, I live in a very dry / mild climate and the car is garaged so I don’t think condensate build up is that much of a concern in my situation.

I’ve also seen post arguing that breather caps don’t allow for proper gas evacuation without the differential pressure aid that routing it to the intake provides. I don’t see how this is the case considering the PCV (correct me if I’m wrong) is basically a spring-loaded check valve that operates only when there is positive pressure in the crankcase.

Any thoughts???
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ahl395

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When doing breathers you gut or remove the PCV valve. At that point it is literally just a hole in the top of the crankcase that the pressure can easily escape through. No need for vacuum to pull it out when it can escape through an open hole IMO, the vacuum setup is just for emissions so the oil vapor/gasses don't go into the atmosphere.

Only thing when using breathers is you need to keep up on cleaning them or they will build up oil and drip on your valve covers.
 

I Bleed Ford Blue

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Technically using breathers instead of a PCV system is illegal on a street car. And Living in commifornia, chances are you will get caught. Don't know what the penalty is for removing an emissions control device out there but in the eyes of the state it's the same as removing your cats. If you really want to do breathers, my suggestion, get out of that liberal infested rathole and move to Nevada or Arizona.
 

Zinc03svt

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I ran breathers on my 18 for over 4k miles zero problems except it did pull in more engine/exhaust smell on non recirculated air. Only downside besides being illegal.
 

Jay-rod427

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I did a remote catch can under the rear bumper because with the blower you would have to route to before the blower, therefore sending all the oil water and fuel vapors through the blower intercooler throttle body and intake. Gunking all those up with crap over time which would require a ton of liberal tears to clean all that stuff off. By making it remote it also makes it very difficult to pull anything back into the engine since it doesn't have the check valve anymore. Breathers direct on the valve cover can cause some issues as they allow moisture back in the engine easily if you remove the pcv check valve.
 

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DiabloStang

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I ran breathers on my 18 for over 4k miles zero problems except it did pull in more engine/exhaust smell on non recirculated air. Only downside besides being illegal.
Did you pull the PCV valves out or just secure the filter to them. I didn’t plan on pull the check valve out.
 
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DiabloStang

DiabloStang

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PCV was probably the first emissions control and eliminated half (half!) of the pollution from our engines. Besides that by burning the fumes it also keeps the engine cleaner and helps the oil to last longer. It doesn't reduce power and causes no problems.
There is no good reason to remove it.
There is no way it keeps the engine cleaner. There is black sludge in my intake tubing and intercooler. Before I supercharged it I had a catch can that would be filled with oil every 5k. No doubt the PCV system is better for the engine but routing it back to the intake is def not good for it. This is why all the cars with direct inject are having a problem with there intake valves getting gunked up before 100k (fuel normally injected into the intake manifold would clean the valves). In a perfect world all new cars would be installed with catch cans but the reality is no one would clean them.
 

ahl395

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PCV was probably the first emissions control and eliminated half (half!) of the pollution from our engines. Besides that by burning the fumes it also keeps the engine cleaner and helps the oil to last longer. It doesn't reduce power and causes no problems.
There is no good reason to remove it.
On supercharged setups I've seen PCV blow by all over the impeller and intake piping. No thanks! It will also dilute your AFR.

Did you pull the PCV valves out or just secure the filter to them. I didn’t plan on pull the check valve out.
I could be wrong but I believe If you dont gut or remove the check valve it wont be able to vent properly. That valve needs vacuum to open. Without vacuum that side of the block wont be able to vent pressure properly if the check valve is installed.
 

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your better off with a good catch can, i run a moroso can with a top breather filter thats on the can works awesome. some 10an fittings, hose and done least on my passenger side , and i located it under the plastic rad cover near my headlight , i didnt gut the pcv either .. i did cap the line that comes from my cai around the backside of my supercharger and tees to the line that roush used, now mines just a hose from the pcv to the can, then back up to my s/c.. never a problem and its a easy pop off empty then back to rippin it
 

Zinc03svt

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Did you pull the PCV valves out or just secure the filter to them. I didn’t plan on pull the check valve out.
There is only one check valve on passenger side. Yes, you want to pull that out. Small flat head and pop out spring and plunger.
 

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Technically using breathers instead of a PCV system is illegal on a street car. And Living in commifornia, chances are you will get caught. Don't know what the penalty is for removing an emissions control device out there but in the eyes of the state it's the same as removing your cats. If you really want to do breathers, my suggestion, get out of that liberal infested rathole and move to Nevada or Arizona.
That state is like, too liberal in views, but too authoritarian in practice. Like what the hell!? The worst of two opposing ideology, rolled into one.
 

dn1984

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your engine will be more reliable long term with the PCV system in place. that's why a catch can is a good idea. think of how a PCV system works. it uses the engine's VACUUM to remove contaminated air and replace it with fresh air. breathers just kind of let it vent out naturally which is to say with very low velocity and volume. think of this analogy. you rip a nasty fart in your car. do you think it will air out with the car stopped and one window cracked, or moving at 70mph with both windows all the way down. you can even keep farting with both windows down and going 70mph and won't even smell it.

here's another thing to consider. after automakers started using PCV systems, suddenly engines started lasting twice as long. not a coincidence
 

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your engine will be more reliable long term with the PCV system in place. that's why a catch can is a good idea. think of how a PCV system works. it uses the engine's VACUUM to remove contaminated air and replace it with fresh air. breathers just kind of let it vent out naturally which is to say with very low velocity and volume. think of this analogy. you rip a nasty fart in your car. do you think it will air out with the car stopped and one window cracked, or moving at 70mph with both windows all the way down. you can even keep farting with both windows down and going 70mph and won't even smell it.

here's another thing to consider. after automakers started using PCV systems, suddenly engines started lasting twice as long. not a coincidence
Your not even close. The PCV (positive crankcase ventilation) is an emission control device and has absolutely nothing to do with longevity of the engine.

During the combustion process, blowby occurs past the piston rings. On old school engines from the early sixties and before these blowby gases just went out of a breather or simply a draft tube.The PCV was developed to recycle these gases by sucking them into the intake tract thru a check valve. It does not replace the bad air with good or fresh air, it only captures the bad air and recycle it, that's it.

Another option to bypass the pcv is to run a tube down to the exhaust and install a venturi in your exhaust pipe to pull the blowby gases out the exhaust. It's just as clean under the hood as the pcv system but it does not dilute the incoming air/fuel charge. But it is just as bad for the environment as the breathers are and technically illegal on a street car.
 

kent0464

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Could someone smart explain to me why routing a hose to the floor or using filter caps / breathers on the PCV valves is bad or good when applying it to a gen 2 coyote motor? I have a procharged s550 and would like to put a cone filter directly on the head unit (it just looks and sounds way cooler) Doing this would require me to modify the PCV setup ( its currently routed to the intake tube just upstream of the compress suction ).

I’ve seen post arguing that breather caps cause condensation to buildup in the engine, noticing a milk substance when taking the breather caps off. However, I live in a very dry / mild climate and the car is garaged so I don’t think condensate build up is that much of a concern in my situation.

I’ve also seen post arguing that breather caps don’t allow for proper gas evacuation without the differential pressure aid that routing it to the intake provides. I don’t see how this is the case considering the PCV (correct me if I’m wrong) is basically a spring-loaded check valve that operates only when there is positive pressure in the crankcase.

Any thoughts???
Mike above has most of it covered.
To expand, PVCs are “one way” they allow internal gasses/vapors out of the crank case and nothing back in, it’s routed to the area pre throttle body because when the car is running and the throttle body is open there’s a negative pressure which assist in drawing the crank case vapors out of the crank case. Cars have had them in one form or another since the beginning. Crank case vapors can be a bad thing they are flammable/explosive because of the fuel vapors mixed in, which is why they are rerouted to be burned again.
In your case, you have a couple of options.
1.use a bulkhead type fitting in the rubber boot of the cone filter to attach the PVC hose.
2.use a crank case evacuation system to route it to the exhaust after the O2 sensors. Complete system available through SpeedWay, summit, etc.
Option 2 will not pass emissions if that is a thing in your state.
 

CrashOverride

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From an enginerding perspective, venting PCV means your ECU no longer knows how much air you are sticking in the engine as it expects all of the ingested air to be combusted, instead of a fraction of it disappearing, quite literally, into thin air. Can the ECU deal with it, of course, but strictly from a tuning point of view, it's not as accurate.

Ideally you want vacuum on the rings all the time because it helps them seal. PCV can't do it at WOT because there is no vacuum at that point though. If you don't care about the less accurate airflow calculations, yet you want to dump the blowby, then a proper air-oil-separator (The ProVent is quite a good design) works. Alternatively, as already mentioned, dumping the blowby into venturi tubes installed in the exhaust will give you the vacuum needed to help seal the rings - a side benefit is that you get increasing vacuum with increased exhaust flow, so you should get even more vacuum on the rings at WOT. If you are going to run a cat, then I would put the venturi downstream so you don't "fog" the catalyst grid with the un/partially-burned oil vapors.
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